Treatment of pain is of foremost importance in the field of medicine. The pharmacological agents currently used for the treatment of pain may be included, for the most part, in two large groups: opioid compounds and nonsteroidal anti-inflammatory drugs (NSAIDs). The NSAIDs are only useful in the case of light to moderate pain; severe pain has been traditionally treated with opioid compounds. However, said opioid compounds present a series of undesired side effects, such as constipation, respiratory depression, and tolerance and addiction liability.
U.S. Pat. No. 3,652,589 describes a class of analgesic compounds with a structure of substituted cycloalkanol phenol ethers having an amino group of alkaline character in the cycloalkyl ring. Among them, the compound (1R,2R or 1S,2S)-2-[(dimethylamino)methyl]-1-(3-methoxyphenyl)cyclohexanol, commonly known as Tramadol, may be thrown into relief, and it is specifically claimed in said patent. 